Stage drama refers to the art of theater that can be presented on a stage, which can be divided into opera, ballet, drama, mime, puppetry, and so on.
However, in Japan, stage drama usually refers to musical theater.
As for why Japanese musicals are translated as stage dramas, this goes back to translation issues during Taiwan's enthusiasm for Japanese culture.
What Chen Yu had booked for the evening was a very classic piece, "Rokumeikan," whose original work was by the famous Japanese writer Mishima Yukio. "Rokumeikan" is also one of his representative works.
In the Meiji Era, Japan sought to extricate itself from unequal treaties. Diplomats held European-style balls overnight at the Rokumeikan to entertain envoys from various countries, aiming to obtain a status for equal dialogue. This period was also called the Rokumeikan era, represented by Kaoru Inoue, Japan's then foreign minister, and Hirobumi Ito, the prime minister.